Interaction of Single Cells with 2D Organic Monolayers: A Scanning Electrochemical Microscopy Study

Abstract

Cell shape is a valuable indicator of cell health status and interactions with the extracellular materials. With the aim to investigate how individual cells respond to chemical microenvironments, we employed 2D monomolecular layers of small organic molecules, characterized by very low roughness. MCF10A cells were grown on these surfaces and characterized by using scanning electrochemical microscopy. The single cell morphologies were analyzed to define a "figure of merit" for the different cell-surface interactions. Such "figure of merit" quantifies the interaction with the microenvironment. This method is applicable to any cell state (metastatic, physiological or pathological) and any surface.The shape of cells changes according to their physiological status and the interactions established with the surface where they adhere. [1] Both surface structuration and surface functionalization drive cell morphology. [2,3] An understanding of the phenomena affecting its characteristics is strongly needed for several applications. [4] The assessment of cell status from a single cell shape can be a powerful diagnostic source to screen materials for nanoand bio-technological applications (implantable sensors and devices, materials for drug-delivery) and to investigate cell phenotype (e. g. metastatic cells versus normal cells). Confocal microscopy and super-resolution imaging can be applied to analyze cell shapes. In these methods, fluorescent stains or tags are required and even if there is an increasing interest in the synthesis and development of not toxic compounds, it is not trivial to mark the whole volume of the cell. Moreover, the photo-toxicity caused by the high-power lasers used for the excitation of the fluorescence cannot be avoided. Scanning electrochemical microscopy (SECM) allows for a tag free analysis in physiological conditions of cell morphologies. At the same time, SECM can be used to investigate the local reactivity of the substrates where the cells adhere.When dealing with single entities, a great deal of information can be acquired, including access to stochastic phenomena and to data regarding the heterogeneity and the statistics of the system. [5][6][7][8] Here we assess cell-surface interactions by investigating the morphology of individual cells imaged by SECM. The procedure consists in a "training" phase, during which several single cell conformations belonging to three different cell-surface interaction regimes were examined, to learn how to recognize a specific cell condition. The method is an example of "learning process" applied to single entity electrochemistry investigation.In order to train the system, we employed three different kinds of mono-molecular layers of small organic molecules grown on native SiO x . The selected organic materials can be prepared to form surfaces with extremely low roughness (ca. 2 Å ) that differ in chemical functionality. Specifically, Pentacene (P5), [9] a-Sexithiophene (6T) [10] and N,N'-bis(n-octyl)-dicyanoperylene-3,4 : 9,10-bis(dicarboximide) (PDI8-CN 2 ) ...

Self-organization of complete organic monolayers via sequential post-deposition annealing

“…It allows employing such molecules in order to develop functional surfaces with different chemical interfaces. Pentacene and PDI8-CN2 were recently used from this perspective in order to tune the cell-surface interactions [95]. They enable a more precise investigation of the cellsurface interaction, introducing a "morphological figure of merit" for defining it.…”

Differential Entropy: An Appropriate Analysis to Interpret the Shape Complexity of Self-Similar Organic Islands

“…As described above, the second ML grows following the FM growth mode. As well as the native SiO x substrate, a complete 6T ML has a CA = (57 ± 1) degree [ 37 , 106 ], therefore the diffusion length can be assumed comparable with the one on native SiO x . Conversely, the island density is reduced to ~6 μm −2 at 25 °C and ~3 μm −2 at 50 °C.…”

Research advances of scanning electrochemical microscopy in biomedical field

“…(a) 直径25 μm的铂圆盘微电极 [53] ; (b) 玻璃管微电极 [39] ; (c) 碳/玻璃微管双 通道电极 [40] ; (d) 金/玻璃微管微圆环双通道电极 [25] ; (e) 直径114 nm的铂纳米电极 [51] ; (f) 玻璃管纳米电极 [52] (网络版彩图) [58] ; (b) 可编程-SECM表 征细胞原理示意图和对PC12细胞高度、膜通透性和呼吸作用三个参数的连续表征图像 [59] ; (c) 应用纳米电极检测单突触神经 递质的释放过程示意图和结果图 [52] (网络版彩图) [21] ; (b) SECM系统与局部给药和 细胞培养舱结合检测心肌细胞的搏动情况和耗氧量 [22] ; 应用SECM (c) 研究不同硬度基质上心肌细胞的GSH外排通量 [64] , (d) 健康和病理性hmMSCs细胞内的氧化还原状态 [66,67] (网络版彩图) Figure 6 Application examples of SECM in studies of cardiomyocytes. (a) Application of SECM to characterize the pulsation and oxygen consumption of cardiomyocytes [21]; (b) Application of SECM combined with micropipette injection system and cell culture chamber to detect the pulsation and oxygen consumption of cardiomyocytes [22]; Applications of SECM to investigate (c) the efflux of GSH released from cardiomyocytes cultured on the substrates with different stiffness [64] [69] ; (b) SECM用于检测细 胞表面SEAP表达的原理示意图和微孔阵列中HeLa细胞的荧光和SEAP表达的SECM图像 [71] ; (c) SECM研究GSH外排的原理示 意图和HeLa细胞GSH外排的 SECM图像 [8] ; (d) SECM检测膜渗透性的原理示意图及不同浓度CdCl 2 加入后T24细胞的光学显 微镜照片和FcMeOH扩散的SECM图像 [76] ; (e) SECM检测T24细胞释放H 2 O 2 的原理示意图和不同时间T24细胞外H 2 O 2 电流的 SECM图像 [15] ; (f) 应用镀铂碳纳米电极作SECM探针, 检测乳腺癌细胞(MDA-MB-231、MDA-MB-468、MCF-10A)内ROS/ RNS(H 2 O 2 、ONOO − 、NO和NO 2 − )的伏安图 [16] (网络版彩图) . 之后, Bard课题组 细胞表面不同位置对FcCH 2 OH渗透系数的一致性 [75] .…”